The present invention relates to a key telephone system and, more particularly, to a key telephone system which allows system data to be keyed in from a particular one of a plurality of key telephone stations.
A key telephone system is a customer controlled telephone switching system which is capable of using more than one line by manipulation of service selection pushbuttons, or keys, arranged on a single telephone station set. This kind of system contributes a great deal to efficient utilization of lines within an office.
Usually, system data for defining system operations of key telephone stations somewhat differ from one office to another. Therefore, at the time of installation of a key telephone system in a certain office, the supplier sets system data by manipulating buttons to meet the particular customer's needs. System data of the kind concerned include a ringing assignment for specifying key station sets which ring upon receipt of calls over respective CO lines, a call restriction assignment for determining whether or not to allow origination of a call to CO lines on each of the key station sets, various timer value assignments used in a key telephone system, and assignments of a paging group, a prime line pick up, an attendant station, a private line, a CO line scan, a door phone, and a door phone chime. A system data memory is divided into blocks each of which is assigned to system data which are as analogous to each other as possible. Each block of the system data memory includes a plurality of 1-byte memories which are accessed by memory addresses (FIG. 1). To set various timer counters, for example, memory block "1" is designated first. Then, if the timer is a hooking timer, memory address "1" is designated to set data associated with the relation between each station set and the timer. Where the timer is a pause timer, memory address "2" will be designated for setting associated data. FIG. 2 represents ringing assignment wherein the number of CO lines is assumed to be six and that of station sets, sixteen. In FIG. 2, memory block "2" is designated and, then, memory address "1" so as to set either "0" or " 1" in each of eight bits of the accessed memory address, thereby assigning ringing on the first to eighth station sets for the first CO line. Then, memory address "2" is accessed to set data in respective bits of that address so that a ringing assignment is effected on the nineth to sixteenth station sets for the first CO line. For the second, third, . . . , sixth CO lines, memory addresses "3", "4", "5", "6", . . . , "11", "12", are designated, respectively, and data are set therein.
The above-described manner of memory area allocation, i.e., gathering system data associated with analogous functions in the same block and writing a specific one of the functions by designating a word address, is effective to free the other blocks from being influenced by the writing of the specified one of the functions.
System data are entered by manipulating buttons of one of key station sets which can be switched in a system from the usual operation mode to the system data set mode. The particular key station set used for system data setting is identical with the others concerning the arrangement of buttons on an operation panel; buttons which serve as function buttons in the usual operation mode serve to access the block addresses and memory addresses, for entry of data, etc., in a system data set mode.
Referring to FIG. 3, there is shown a key telephone station set provided with various function buttons, dial buttons, CO buttons, DSS (direct station selection) buttons and the like which serve their so named functions in a usual operation mode. In a system data set mode, on the other hand, the buttons fill the roles of function buttons shown in FIG. 4. That is, in FIG. 4, the DSS buttons are used for accessing memory blocks, the dial buttons (ten keys) for accessing memory addresses, and the CO buttons for writing data in each bit of the accessed memory address.
The functions of the respective buttons in the system data set mode have no relation to the functions of these buttons in the usual operation mode. A person in charge of the assignment, therefore, has to manipulate the buttons with accuracy referring to a table which shows the functions of the buttons in the system data set mode, the addresses which are to receive data and the data to be entered at each address. Such work is labor- and time-consuming.
The need for changing the ringing assignment and call restriction assignment often arises in a office due to changes in office layout, and shifts of workers' positions. The difficulty experienced by the customer in changing system data including the ring assignment and call restriction assignment becomes great if the names or labels of buttons in a usual operation mode have no connection with those in a system data set mode as discussed above.